AM, which operates at a lower frequency, has radio waves with larger wavelengths, meaning they travel farther but struggle to penetrate solid objects like buildings.
Aren’t low frequencies better at penetrating materials?
yes they are, you can detect lower bands pretty much everywhere. The problem is modulation: AM sucks balls when it comes to noise rejection. Some AM stations switch to digital encoding which uses the same band so good propagation + good audio quality within some range. After you get too far away signal just drops, if you’re willing to put up with higher noise level range of normal AM radio is basically global
After you get too far away signal just drops, if you’re willing to put up with higher noise level range of normal AM radio is basically global
This depends very highly on the condition of the ionosphere and its ability to reflect the signal. This doesn’t make its useful range global, even if you can pick up very distant broadcasts occasionally.
On a clear night I can catch a Cardinals game on KMOX on the Indiana/Ohio line. There have been reports of people in Glasgow being able to get the broadcasts. But it’s really only good for talk radio. Any music sounds like shit. But listening to a baseball game on AM radio is such a peaceful way to soend a sunmer evening.
Yes. But any metal in the building that’s smaller than the wavelength of the AM radio frequency which is quite long, will absorb the radio wave so it won’t penetrate the building
wrong
it penetrates buildings just fine
AM FREQUENCIES CANT MELT STEEL BEAMS
With enough power they can
Which gives me a new conspiracy idea…
I think you mean that statement the other way around, and it’s not going to perfectly absorb even in that case unless you have a true faraday cage.
Buildings won’t perfectly absorb signals but it will attenuate the signals that pass through them.
The gaps In a faraday cage determine the maximum wavelength of the electromagnetic signal that can pass through. AM signals have very long wavelengths, and are more likely to get distorted
Any metal in a building will act to distort and absorb signals, the more metal, like rebar in concrete, the less signal can get through.
Examples:
Consider the ocean, ionic water, very difficult to get radio signals because there are so many dense charge carriers to absorb the radio waves.
Consider the earth: sending radio signals through the center of the earth is difficult because of all the metal, electron carriers in the earth itself.
Consider wifi in a modern concrete and rebar office building, one or two rooms over and the signal gets absorbed quite effectively.
I think I understand better where you’re coming from. I have a variety of homemade low frequency antennas, typically on the order of 20 meter wavelength, and I observe lower frequencies clearly get better reception inside buildings. Transmission tends to be more variable because I have an increasingly large near field zone that’s effectively impossible to clear. Indeed, my real world experience has always been the opposite. Lower frequencies appear to get through better, provided you can actually talk out. I usually prefer to modulate the H field because it’s orthogonal to household noise sources and after some distance away doesn’t couple to metal.
I’m not sure why this is. Perhaps buildings are different enough from Faraday cages? Lower frequencies diffract and bend around objects much much more effectively than high frequencies.
I have some RF design engineer friends and I’ll ask them why my experience is different.
If you find your having better reception indoors then outdoors then the signal your looking for is being attenuated less then the noise/interference is being attenuated by the structure your housing your antenna in.
Low power noise is less likely to bounce around and come in the building from a different angle, but AM is famous for its ability to propagate.
Consider driving a car into a parking structure with the radio on, listening to AM radio. You can hear the signal getting weaker, not stronger. Until you get to the roof. If you go into the basement, you only hear local noise
Basically every tunnel and such here has an AM station to tune into for traffic/weather conditions (weather can be wildly different at the end of some longer tunnels, especially the ones that gain elevation or open to a bridge over a valley).
Japan actually has more of an excuse for this than somewhere like the United States or Russia, just simply due to its size. AM radio is pretty much required in countries as large as the US or Russia. Sure, maybe there should be fewer AM stations with more power, but AM should not go away entirely.
This could be us in the US but lobbyists be playin
Other way around. Lobbyists for the auto industry want to get rid of AM to save themselves money, but AM is more reliable than FM for emergency alerts (further range, can penetrate buildings).
last time I tuned into AM radio, I got shivers with the amount of hate consistently being spouted on each station I tuned to.
I wouldn’t shed a tear if all that hate suddenly vanished, but I’d rather it not be because automakers wanted to save $0.05 per vehicle.
It’s true that it’s largely used for spouting hate in the US. It is also used by transportation departments to share travel warnings, but I doubt that gets a whole lot of usage under normal circumstances.
If AM goes away, the hatemongers will just find another platform.
I understand the benefits for emergency alerts but don’t we also have WEA on phones for that same reason? Let’s be honest, the only time we ever get a big one on our phones it’ll either be for something terrible we have no control over, or the president announcing pee is stored in the balls.
In general, AM radio is the playground of the right wing and I’d love nothing more than to fuck them over because that’s the only thing they’ve ever known. They’ll survive on FM, sure, but as they like to say: The cruelty is the point. Emergency broadcasts can be made on FM, its not as big of a loss as we fear it will be.
In general, AM radio is the playground of the right wing and I’d love nothing more than to fuck them over because that’s the only thing they’ve ever known.
This is an unhinged take. Kill off the most simple to implement and farthest travelling radio system that would be essential in the event of a nationwide blackout or other emergency (and let the spectrum get sold off to some megacorp), just to own the cons because they broadcast stuff that nobody listens to anyway?
Emergency broadcasts can be made on FM, its not as big of a loss as we fear it will be.
It would be a big loss. FM does not travel beyond the horizon. AM does not require a functioning electrical grid powering the whole country and hundreds of towers linked to telecom services. AM receivers can be built with household scrap. We can get by currently with FM for emergencies, that’s what NOAA weather radio is, but vast swaths of the desert and rural areas are presently left uncovered, and a nationwide power grid or telecom outage would severely impact the service.
I know it may sound crazy, but not everyone is driving around with a phone. That’s why you sometimes see updatable signs on highways telling you what AM station to tune into for whatever alert it is they have to issue .
You’re right that AM is mostly used by right-wing hatemongers in the US, but they will always find something else. It’s not the platform that’s the problem.
It’s a bit funny to me that this move is coming from Japan. It’s been a little more than a decade now, but I used to live in Japan, and good radio stations playing music were all over AM radio when I was there. Maybe it’s regional.
